Composition and Method to Form a Composite Core Material

ABSTRACT

A composite core material and methods for making same are disclosed herein. The composite core material comprises mineral filler discontinuous portions disposed in a continuous encapsulating resin. Further, the method for forming a composite core material comprises the steps of forming a mixture comprising mineral filler, an encapsulating prepolymer, and a polymerization catalyst; disposing the mixture onto a moving belt; and polymerizing said encapsulating prepolymer to form a composite core material comprising mineral filler discontinuous portions disposed in a continuous encapsulating resin.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and is a continuation of U.S.application Ser. No. 17/322,372 filed on May 17, 2021 which issues asU.S. Pat. No. 11,760,862 on Sep. 19, 2023 (Docket No. COMP-017), whichis a continuation of U.S. application Ser. No. 15/830,808 filed on Dec.4, 2017 which issued as U.S. Pat. No. 11,008,438 on May 18, 2021 (DocketNo. COMP-004), which claims priority to U.S. Provisional Application No.62/429,535 filed Dec. 2, 2016 (Docket No. COMP-003). Each of theaforementioned patent applications is herein incorporated by referencein their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable to this application.

BACKGROUND

The described example embodiments in general relate to a composite corematerial, methods of making same, methods of making a composite materialwith same, and of testing compressive strength thereof.

A composite material (also called a composition material or shortened tocomposite) is a material made from two or more constituent materialswith significantly different physical or chemical properties that, whencombined, produce a material with characteristics different from theindividual components. The individual components remain separate anddistinct within the finished structure. The new material may bepreferred for many reasons: common examples include materials which arestronger, lighter, or less expensive when compared to traditionalmaterials.

Transportation, construction and aerospace are the largest marketsegments within the composites industry recently, representing 62percent of its total value. Development of low-cost and high-strengthcomposite material to be used in those industries is important.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flow chart of forming a composite core material;and

FIG. 2 is a flow chart of forming a composite product with a compositecore material in FIG. 1 .

DETAILED DESCRIPTION

Some of the various embodiments of the present disclosures are describedin preferred embodiments in the following description with reference tothe Figures, in which like numbers represent the same or similarelements. Reference throughout this specification to “one embodiment,”“an embodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

The described features, structures, or characteristics of embodimentsdisclosed herein may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details arerecited to provide a thorough understanding of embodiments of theinvention. One skilled in the relevant art will recognize, however, thatthe embodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of the claimedinvention.

Embodiments of Applicant's disclosure describe compositions of acomposite core material, methods to form same, methods to form acomposite material with same, and methods to test the compressivestrength of same.

In certain embodiments, a composite core material comprises one or moremineral filler discontinuous portions disposed in a continuousencapsulating resin. In certain embodiments, the mineral filler iscalcium sulfate. In other embodiments, the mineral filler is calciumcarbonate. In other embodiments, the mineral filler is aluminumtrihydrate. In other embodiments, the mineral filler is talc. In otherembodiments, the mineral filler is gypsum. In other embodiments, themineral filler is magnesium hydroxide. In other embodiments, the mineralfiller is dolomite. In other embodiments, the mineral filler is anycombination of calcium sulfate, calcium carbonate, aluminum trihydrate,talc, gypsum, magnesium hydroxide, and dolomite.

Further, in certain embodiments, the calcium sulfate comprises hydratesthereof. In certain embodiments a calcium sulfate hydrate is calciumsulfate hemihydrate having a formula of CaSO.sub.4.(nH.sub.2O), whereinn is equal to or greater than 0.5 and equal to or less than 0.8. Inother embodiments, the calcium sulfate hydrate is calcium sulfatedihydrate having a formula of CaSO.sub.4.2H.sub.2O. In yet otherembodiments, the calcium sulfate hydrate can be a combination of calciumsulfate hemihydrate and calcium sulfate dihydrate. The weight percentageof the calcium sulfate hemihydrate in the combination of calcium sulfatehemihydrate and calcium sulfate dihydrate ranges from about 5% to about95%, e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%,70%, 75%, 80%, 85%, 90% or another concentration of the calcium sulfatedihydrate can be from about 5% to about 95%. The weight percentage ofthe calcium sulfate dihydrate ranges from about 95% to about 5%, e.g.,90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%,20%, 15%, 10% or another concentration of the calcium sulfate dihydratecan be from about 95% to about 5%. As used herein, “about” is used todescribe a difference of 10% in any measurements.

In some embodiments, the continuous encapsulating resin is a polymerizedproduct of polyester resins having a structure of:

wherein n is from about 3 to about 6. In some embodiments, the polyesterresins are 404 Isophthalic Resin purchased from US Composites. Thepolylite polyester resin 404 is a rigid, medium reactivity, premiumchemical resistant, isophthalic based. This resin has low viscosity andis thixotropic. In other embodiments, the polyester resins are AROPOLunsaturated polyester resins purchased from Ashland. In yet otherembodiments, the polyester resins are HETRON FR 650 Series flameretardant resins purchased from Ashland. Composites made with HETRON FR650 Series resins have been tested and have achieved a Class 1 FlameSpread per ASTM E-84 without addition of synergists such as antimonytrioxide. In still yet other embodiments, MODAR acrylic modified resinspurchased from Ashland are used to achieve fire retardant effects in thecomposite core materials. These two examples of the fire retardantresins are not meant to be limiting as other fire retardant resins maybe used.

In other embodiments, the continuous encapsulating resin is apolymerized product of vinyl ester resins having a structure of:

wherein n is 1 to about 2, where R.sub.1 is hydrogen or alkyl, R.sub.2is hydrogen or alkyl, R.sub.3 is hydrogen or alkyl, R.sub.4 is hydrogenor alkyl. In some embodiments, the vinyl ester resins are TAP Marinevinyl ester resin purchased from TAP Plastics.

In yet other embodiments, the continuous encapsulating resin is apolymerized product of a combination of the polyester resins and thevinyl ester resins. The weight percentage of the polyester resin rangesfrom about 5% to about 95%, e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%,45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or anotherconcentration of the polyester resin from can be from about 5% to about95%. The weight percentage of the vinyl ester resin ranges from about95% to about 5%, e.g., 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%,40%, 35%, 30%, 25%, 20%, 15%, 10% or another concentration of the vinylester resin from can be from about 95% to about 5%.

In yet another embodiment, the continuous encapsulating resin comprisesabout 38.3139% by weight styrene, about 0.3% by weight dimethylaniline,about 0.195% by weight cobalt-2-ethylhexanoate.

The respective weight percentages of the calcium sulfate discontinuousportion and the continuous encapsulating resins in the composite corematerial can vary. In some embodiments, the composite core materialcomprises about 60% to about 80% by weight the calcium sulfatediscontinuous portion and about 20% to about 40% by weight thecontinuous encapsulating resins. In other embodiments, the compositecore material comprises about 80% by weight the calcium sulfatediscontinuous portion and about 20% by weight the continuousencapsulating resins and the composite core material has a density ofabout 2 lbs/feet.sup.2.

FIG. 1 summarizes an embodiment of a method to make the composite corematerial. Referring to FIG. 1 , in step 100, calcium sulfate and/orhydrates thereof, an encapsulating prepolymer, and a polymerizationcatalyst are provided. In some embodiments, calcium sulfate dihydratehaving a formula of CaSO.sub.4.2H.sub.20. In other embodiments, calciumsulfate hemihydrate having a formula of CaSO.sub.4.(nH.sub.20), whereinn is equal to or greater than 0.5 and equal to or less than 0.8. In someembodiments, polyester resins are used. In other embodiments, vinylester resins are used. In yet other embodiments, styrene-based resinsare used. In some embodiments, a polymerization catalyst is 2-Butanoneperoxide, having a structure of

2-Butanone peroxide has a molecular weight of about 210.22 and a densityof about 1.053 g/ml at 20.degree. C. In other embodiments, any catalystknown to a person in the art that can facilitate the polymerization ofthe encapsulating resin to encapsulate the discontinuous calcium sulfateportions can be employed.

In step 110, all the materials provided in step 100 are mixed to form afirst mixture comprising calcium sulfate and/or hydrates thereof, theencapsulating prepolymer, and the polymerization catalyst. In certainembodiments, the polymerization catalyst has a concentration of about 1%to 2.5% by weight in a second mixture of the encapsulating prepolymerand the polymerization catalyst. The weight percentage of thepolymerization catalyst can be about 1%, 1.25%, 1.5%, 1.75%, 2%, 2.25%,or any other weight percentage that ranges from 1% to 2.5%.

Now in step 120, the first mixture comprising calcium sulfate and/orhydrates thereof, an encapsulating prepolymer, and a polymerizationcatalyst is poured onto a moving belt. In certain embodiments, themoving belt is heated to facilitate the polymerization of theencapsulating prepolymer. In certain embodiments, a mesh assembly layson top of the moving belt and the first mixture is spread evenly overthe mesh assembly. In some embodiments, the mesh assembly has a width ofabout 20 inches to about 60 inches. In other embodiments, the meshassembly has a width of 24 inches. In some embodiments, the meshassembly is a fiberglass mesh assembly. In other embodiments, the meshassembly is a wire mesh assembly. The fiberglass and the wire meshassemblies are not meant to be limiting. In yet other embodiments, othersuitable materials known to a person skilled in the art can be used tomake the mesh assembly.

In step 130, the first mixture spread evenly over the mesh assembly iscured so that the encapsulating prepolymer is polymerized to form asheet of composite core material comprising calcium sulfatediscontinuous portions disposed in a continuous encapsulating resin. Incertain embodiments, the sheet of composite core material has athickness of about 0.0625 inches to about 1 inch. In some embodiments,the sheet of composite core material has a thickness of about 0.25inches.

Further, in step 140, a decision is made as to whether the sheet of thecomposite core material needs to be scored into a plurality ofreinforcing blocks. In certain embodiments, smaller blocks of compositecore materials are warranted. In step 150, the sheet of the compositecore material is scored into a plurality of reinforcing blocks. Incertain embodiments, each reinforcing block has a width of about 0.5inches to about 4 inches and a length of about 0.5 inches to about 4inches. In addition, in step 160, the sheet of the composite corematerial is cut into a plurality of pieces with any desirable length. Inother embodiments, the sheet of composite core material is maintained ina solid sheet without scoring in step 152. For convenience oftransportation, the sheet of composite core material can be cut into asmaller sheet of 48 inches wide by 48 inches long, 48 inches wide by 96inches long, or any other width and length according to differentrequirements.

FIG. 2 summarizes Applicant's method to utilize the composite corematerial that is described below in certain embodiments in manufacturingappliances, machines, automobiles, and etc. Referring to FIG. 2 , instep 200, composite core materials formed in step 130 (FIG. 1 ) andshaped in step 130 or step 160 (FIG. 1 ) are provided.

In step 210, a mold of appliances, machines, automobiles, or etc. isprovided. For example, if a user would like to build a bathtubincorporating the composite core materials, the user would start with abathtub mold, i.e., a hollow form or matric for giving a particularshape of a bathtub. If a user would like to build a truck bed utilizingthe composite core materials, the user would first supply a truck bedmold, i.e., a hollow form or matric for giving a particular shape of atruck bed.

After selecting a particular mold of a particular shape, a first layerof gel coat with a polymerization catalyst at a thickness of about 15mils is applied to the mold in step 220. As described herein, “mil” isdefined as a unit of length equal to about 1/1000 inch used especiallyin measuring thickness (as of plastic films). The thickness of the gelcoat is not limiting. According to the type of mold selected andstrength requirement of the final product, the thickness of the gelcoated applied varies accordingly. As a person skilled in the art wouldappreciate, a gel coat is a material used to provide a high-qualityfinish on a visible surface of a fiber-reinforced composite. The mostcommon gel coats are based on epoxy or unsaturated polyester resinchemistry. Gel coats are modified resins which are applied to molds inthe liquid state. They are cured to form crosslinked polymers and aresubsequently backed with composite polymer matrices, often mixtures ofpolyester resin and fiberglass or epoxy resin with glass. Themanufactured component, when sufficiently cured and removed from themold, presents the gel coated surface. In certain embodiments, this ispigmented to provide a colored, glossy surface which improves theaesthetic appearance of the article, such as a counter made withcultured marble. In some embodiment, the first layer of gel coat issprayed from a spraying apparatus onto the side of the selected moldfrom step 210. In other embodiments, the first layer of gel coat isbrushed onto the selected mold from step 210. Other applying methodsknow to a person skilled in the art can be used herein. In certainembodiments, the polymerization catalyst has a concentration of about 1%to about 2.5% by weight in the mixture of the gel coat and thepolymerization catalyst. The weight percentage of the polymerizationcatalyst can be about 1%, 1.25%, 1.5%, 1.75%, 2%, 2.25%, or any otherweight percentage that ranges from 1% to 2.5%.

In step 230, the first layer of gel coat is dried but not completelycured on the side of the selected mold from step 210 at a temperature ofabout 100.degree. C. for about 5 minutes. The particular temperature andthe length of time disclosed herein are not limiting, with variousdifferent types of gel coat applied, the particular temperature and thelength of the time for curing vary accordingly.

After the first layer of gel coat is dried but not completely cured, instep 240, a second layer of laminate comprising of a third mixture isapplied to the dried first layer of gel coat in step 230. Further, thethird mixture comprises calcium sulfate and/or hydrates thereof, anencapsulating prepolymer, a polymerization catalyst, and a plurality offiberglass pieces. In certain embodiments, the third mixture comprisesabout 50% to 54% of calcium sulfate and/or hydrates thereof, about 34%to 38% of the encapsulating prepolymer, and about 8% to 16% of theplurality of fiberglass pieces. In some embodiments, the third mixturecomprises about 52.8% of calcium sulfate and/or hydrates thereof, about35.2% of the encapsulating prepolymer, and about 12% of the plurality offiberglass pieces. In certain embodiments, the polymerization catalysthas a concentration of about 1% to 2.5% by weight in the mixture of theencapsulating prepolymer and the polymerization catalyst. The weightpercentage of the polymerization catalyst can be about 1%, 1.25%, 1.5%,1.75%, 2%, 2.25%, or any other weight percentage that ranges from 1% to2.5%.

Because the first layer of gel coat is not completely cured but dried,the first layer of gel coat is still sticky to the touch. When applyingthe second layer of laminate in step 240, the second layer of laminatedoes not leak through the dried first layer of gel coat. In certainembodiments, the second layer of laminate is applied at a thickness ofabout 50 to 75 mils. The thickness of the laminate layer is notlimiting. According to the type of mold selected and strengthrequirement of the final product, the thickness of the laminate layerapplied varies accordingly. Further, to ensure even application of thelaminate layer, a suitable appliance is used to roll out any possiblebubbles presented in the laminate layer.

In step 250, without solidifying the laminate layer in step 240,applying a plurality of pieces of the composite core materials from step160 to the uncured laminate layer. Depends on different types of molds,sheets of the composite core materials from step 130 can applied to theuncured laminate layer. In certain embodiments, a thickness of about 50mil of the composite core material is preferred. However, the thicknessof the composite core material is not limiting. According to the type ofmold selected and strength requirement of the final product, thethickness of the composite core material applied varies accordingly.

After applying pieces of the composite core material, another layer ofthe laminate is applied to pieces of composite core material in step260. The laminate has the same composition as the laminate layerdescribed in step 240. In certain embodiments, the thickness of thelaminate layer in step 260 is about 50 to about 75 mil. Similarly, thethickness of the laminate layer is not limiting. According to the typeof mold selected and strength requirement of the final product, thethickness of the laminate layer applied varies accordingly. After curingthe second layer of laminate in step 260, a composite materialincorporating the composite core materials is formed in step 270. Theformed composite material encloses the mold selected in step 210.

Further, in step 280, a decision is made whether a compressive strengthtesting is needed on the piece of the composite material. If yes, step280 transitions to step 284, one or more compressive strength tests willbe carried out. If no, step 280 transitions to step 282. As describedherein, compressive strength or compression strength is the capacity ofa material or structure to withstand compressive loads, as opposed totensile strength, which withstands loads tending to elongate. In otherwords, compressive strength resists compression (being pushed together),whereas tensile strength resists tension (being pulled apart). In thestudy of strength of materials, tensile strength, compressive strength,and shear strength can be analyzed independently.

EXAMPLE 1

A compressive strength test is performed on the piece of the compositematerial formed in step 250. A 3 inch disc on a hydraulic cylinderapplied compressive forces to the side of the piece of the compositematerial where the first and the second coats are both applied to testboth deflection and bond strength of the piece of the compositematerial. The composite material did not fail when a pressure of 2,000psi was applied.

While the preferred embodiments have been illustrated in detail, itshould be apparent that modifications and adaptations to thoseembodiments may occur to one skilled in the art without departing fromthe scope of the claimed invention.

What is claimed is:
 1. A method to form a composite core material, comprising polymerizing an encapsulating prepolymer of a first mixture to form a sheet of composite material comprising calcium sulfate or calcium sulfate hydrate discontinuous portions disposed in a continuous encapsulating resin; cutting the sheet of composite material into a plurality of pieces of the composite material; applying a gel coat having a polymerization catalyst to a mold and drying the gel coat without completely curing the gel coat; applying a first layer of a laminate to the dried gel coat, wherein the laminate includes a polymerization catalyst and plurality of fiberglass pieces; without curing the first layer of the laminate applied to the dried gel coat, applying at least a portion of the plurality of pieces of the composite material to the first layer of the laminate; applying a second layer of the laminate to the portion of the plurality of pieces of the composite material, which is atop the first layer of the laminate; and curing the second layer of the laminate to enclose the mold.
 2. The method of claim 1, wherein the first mixture is comprised of (a) one or more of a calcium sulfate and a hydrate of the calcium sulfate; (b) the encapsulating prepolymer; and (c) a polymerization catalyst.
 3. The method of claim 2, wherein the polymerization catalyst of the first mixture is comprised of 2-Butanone peroxide.
 4. The method of claim 2, wherein polymerizing the encapsulating prepolymer of the first mixture includes curing the one or more of the calcium sulfate and the hydrate of the calcium sulfate, the encapsulating prepolymer and the polymerization catalyst of the first mixture.
 5. The method of claim 2, wherein the encapsulating prepolymer of the first mixture is selected from the group consisting of polyester resins, vinyl ester resins, fire retardant resins and any combinations thereof.
 6. The method of claim 1, wherein the calcium sulfate hydrate of the first mixture is selected from the group consisting of calcium sulfate hemihydrate having a formula of CaSO4·(nH2O), wherein n is equal to or greater than 0.5 and equal to or less than 0.8; and calcium sulfate dihydrate having a formula of CaSO4·2H2O.
 7. The method of claim 1, wherein the sheet of composite core material has a thickness of 0.0625 inches to 1 inch.
 8. The method of claim 1, wherein, prior to polymerizing the encapsulating prepolymer of the first mixture, the method further comprises: forming the first mixture, which is comprised of: (a) the one or more of the calcium sulfate and the hydrate of the calcium sulfate; (b) the encapsulating prepolymer; and (c) a polymerization catalyst; and disposing the first mixture onto a heated moving belt.
 9. The method of claim 8, wherein the heated moving belt comprises a mesh assembly.
 10. The method of claim 1, wherein the gel coat includes a polymerization catalyst.
 11. The method of claim 1, further comprising: forming a second mixture to create the laminate, the second mixture comprising: (a) one or more of a calcium sulfate and a hydrate of the calcium sulfate; (b) an encapsulating prepolymer; (c) the polymerization catalyst; and (d) the plurality of fiberglass pieces.
 12. The method of claim 11, wherein the encapsulating prepolymer of the second mixture is selected from the group consisting of polyester resins, vinyl ester resins, fire retardant resins and any combinations thereof.
 13. The method of claim 1, wherein applying the gel coat to the mold comprises spraying the gel coat on the mold.
 14. The method of claim 1, wherein the applying the gel coat to the mold comprises brushing the gel coat on the mold.
 15. The method of claim 1, wherein the gel coating is pigmented. 